A multilayer capacitor, as a multilayer electronic component, is formed of a dielectric material, and since the dielectric material may have piezoelectric properties, the dielectric material may be deformed in synchronization with a voltage applied thereto.
When a period of the applied voltage is within an audible frequency band, displacement thereof becomes vibrations which may be transmitted through solders to vibrate a board and lead to sound being emitted from the board. Such sound is known as acoustic noise.
When an operating environment of a device is quiet, the acoustic noise may be perceived by a user as an abnormal sound and the user may feel that the device has a problem. Further, in a device having an audio circuit, acoustic noise may be superimposed on an audio output to degrade device quality.
Apart from the acoustic noise perceived by the human ear, the occurrence of piezoelectric vibrations of a multilayer capacitor in a high frequency range of 20 kHz or higher causes malfunctioning of various sensors used in IT and industrial/electrical fields.